• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.416-417
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• 2006

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely [2-(2-hydroxyphenyl)benzoxazole] ($Zn(HPB)_2$) and [(2-(2-hydroxyphenyl)benzoxazole)(8-hydoxyquinoline)] (Zn(HPB)q), which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and Zn(HPB)q. The fundamental structures of the white OLEDs were ITO/PEDOT:PSS (23 nm)/NPB (40 nm)/$Zn(HPB)_2$ (40 nm)/Zn(HPB)q (20 nm)/$Alq_3$ (10 nm)/LiAl (120 nm). As a result, we obtained a maximum luminance of $15325\;cd/m^2$ at a current density of $997\;mA/cm^2$. The CIE(Commission International de l'Eclairage) coordinates are (0.28, 0.35) at an applied voltage of 9.75 V.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.2018-2019
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• 2007

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely $Zn(HPB)_2$ and Zn(HPB)q, which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and Zn(HPB)q. The fundamental structures of the white OLEDs were ITO / NPB (40 nm) / $Zn(HPB)_2$ (40 nm) / Zn(HPB)q (20 nm) / LiAl (120nm). As a result, we obtained a maximum luminance of $15325cd/m^2$ at a current density of $997\;mA/cm^2$. The CIE (Commission International de l'Eclairage) coordinates are (0.28, 0.35) at an applied voltage of 9.75 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.447-448
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• 2005

Recently, organic light emitting diodes(OLEDs) is widely used as one of the information display techniques. We synthesized 2-(2-hydroxyphenyl)benzoxazole($Zn(HPB)_2$). We studied the luminescent properties of OLEDs using $Zn(HPB)_2$. The ionization potential(IP) and the electron affinity(EA) of $Zn(HPB)_2$ investigated using cyclic-voltammetry(C-V). The JP, EA and Eg were 6.5eV, 3.0eV and 3.5eV, respectively. The PL and EL spectra of $Zn(HPB)_2$ were observed at the wavelength of 4S0nm. We used $Zn(HPB)_2$ as an emitting layer and hole blocking layer. At the experiment about hole blocking effect, we inserted $Zn(HPB)_2$ between emitting material layer(EML) and cathode, and hole transport layer(HTL) and emitting material layer(EML). We measured current density-voltage and luminance-voltage characteristics at room temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.12
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• pp.1139-1142
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• 2005

Recently, organic light emitting diodes(OLEDs) is widely used as one of the information display techniques. We synthesized 2-(2-hydroxyphenyl)benzoxazole($Zn(HPB)_2$). We studied the luminescent properties of OLEDs using $Zn(HPB)_2$. The ionization potential(IP) and the electron affinity(EA) of $Zn(HPB)_2$ investigated using cyclic-voltammetry(C-V). The IP and EA were 6.5 eV and 3.0 eV, respectively. The PL and EL spectra of $Zn(HPB)_2$ were observed at the wavelength of 450 nm. We used $Zn(HPB)_2$ as an emitting layer and hole blocking layer. At the experiment about hole blocking effect, we inserted $Zn(HPB)_2$ between emiting material layer(EML) and cathode, and between hole transport layer(HTL) and emitting material layer(EML). We measured current density-voltage and luminance-voltage characteristics at room temperature.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.927-931
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• 2010

Recently, high luminance and high efficiency were realized in OLED with multilayer structure including emitting materials such as metal-chelate complexes. We synthesized a new luminescent material, namely, [2-(2-hydroxyphenyl)quinoline] (Zn(HPB)q) which has low molecular compound and emitted in yellowish green region. The ionization potential(IP) and electron affinity(EA) of Zn(HPB)q were measured by cyclic-voltammetry(CV). As a result, IP and EA of Zn(HPB)q were calculated 6.8 eV and 3.5 eV, respectively. We fabricated the devices and observed the possibility of Zn(HPB)q as electron transporting layer. We have obtained an improvement of luminance and decrease of turn-on voltage using Zn(HPB)q as electron transporting layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.23-24
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• 2006

We have synthesized electroluminescence materials. including [2-(2-hydroxyphenyl)benzoxazole] (Zn(HPB)$_2$), [(2-(2-hydroxyphenyl)benzoxazole)(8-hydoxyquinoline)] (Zn(HPB)q) and [(1, 10-phenanthroline)(8-hydroxyquinoline)] Zn(phen)q. The ionization potential (IP) and electron affinity (EA) of each Zn-complex was measured using cyclic-voltammetry (C-V). Basing on the consideration of matched in the energy levels of the materials. We investigated the electron transporting properties of Zn(HPB)q and Zn(phen)q compared with $Alq_3$, and also we investigated the hole blocking properties of Zn(HPB)$_2$, compared with BCP. As a result, we used Zn-complex to enhance the performance of OLED. Therefore, we demonstrate that Zn(HPB)q and Zn(phen)q are useful as an electron transporting material. Zn(HPB)$_2$ is also good a hole blocking material.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2240-2244
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• 2010

We have studied white OLED using two types of Zn-complexes as a emitting layer. We synthesized new emissive materials $Zn(HPQ)_2$ as a yellow emitting material and $Zn(HPB)_2$ as a blue emitting material. Zn-complexes have a low molecular compound and thermal stability. The fundamental structures of the fabricated OLED was ITO / NPB (40nm) / $Zn(HPB)_2$ (30nm) / $Zn(HPQ)_2$ / LiF / Al. We varied the thickness of the $Zn(HPQ)_2$ layer 20, 30 40 nm. When the thickness of the $Zn(HPQ)_2$ layer was 20 nm, white emission was achieved. The maximum luminance was 12,000 cd/$m^2$ at a current density of 800 mA/$cm^2$. The CIE coordinates of the white emission was (0.319. 0.338) at an applied voltage of 10 V.

• Proceedings of the KIEE Conference
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• 2008.05a
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• pp.167-168
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• 2008

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely $Zn(HPB)_2$ and Zn(HPB)q, which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and $Zn(PQ)_2$. The fundamental structures of the white OLEDs were ITO / NPB (40 nm) / $Zn(HPB)_2$ (40 nm) / $Zn(PQ)_2$ (20 nm) / LiAl (120 nm). As a result, we obtained a maximum luminance of $4200cd/m^2$ at a current density of $440mA/cm^2$. The CIE (Commission International de l'Eclairage) coordinates are (0.319, 0.338) at an applied voltage of 10 V.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.89-90
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• 2006

We synthesized emissive materiaJs, nameJy $Zn(HPB)_2$. The fundamentaJ structures of the OLEDs were ITO / NPB (40 nm) $Zn(HPB)_2$ (40 nm) / $Alq_3$:DCJTB (20, 30, or 40 nm) / LiF / AI. We varied the thickness of $Alq_3$:DCJTB from 20 nm to 40nm. We measured current density-voJtage and luminance-voJtage characteristics at room temperature. When the thickness of the Alq3:DCJTB layer was 40 nm, white emission is achieved. The CIE coordinates are (0.32, 0.33) at an applied voltage of 14V.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.9
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• pp.571-575
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• 2014

We synthesized new materials of $Zn(HPB)_2$ and Ir-complexes as blue or red emitting material. We fabricated white Organic Light Emitting Diodes (OLED) by using $Zn(HPB)_2$ for the blue emitting layer, Ir-complexes for the red emitting layer and $Alq_3$ for the green emitting layer. We fabricated white OLED by using double emitting layers of $Zn(HPB)_2$:Ir-complexes and $Alq_3$. The doping rate of Ir-complexes was varied, such as 0.2%, 0.4%, 0.6%, and 0.8%, respectively. When the doping rate of $Zn(HPB)_2$:Ir-complexes was 0.6%, white emission was achieved. The Commission Internationale de l'Eclairage (CIE) coordinates of the white emission was (0.322, 0.312).